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Author Topic: P1545 and p1579 - engine cuts out and hunts for revs on idle  (Read 168 times)

Offline Clarkj93

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Noticed last couple days sometimes it's taken longer than usual to start, felt like giving some throttle helped get it going as well. Just now it cut out while off throttle at about 20mph down my estate, it starts back up fine but then cuts out again unless I'm giving the engine some revs.  Got it home and it continued to cut out, holding the revs at about 2.5/3k for a couple mins seems to sort it out and now idles fine again.

Quick scan returned the following:
P1545 Throttle valve control system Malfunction
P1579 Throttle valve control unit Adaption not initiated

Didn't feel like there was a limp mode though and no check engine light. No work done on the engine for well over a month now so seems out of the blue.

Going to try a throttle body alignment in a bit and see what happens if the issue is still re-creatable. Thoughts?

Offline Pudding

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Re: P1545 and p1579 - engine cuts out and hunts for revs on idle
« Reply #1 on: June 20, 2022, 01:38:25 pm »
Seems pretty clear cut there mate.  It's either a knackered throttle or it's wiring harness is chaffed through and shorting out. Both are known issues on the GTI.

At least you've got a fault code! Whenever mine does things like that out of the blue, absolutely jack all fault codes  :grin:

Go into basic settings and run the throttle adaptation. I think it runs through 8 checks from memory and should say "ADP. OK" at the end if it passes.

Although it may pass a test, that isn't to say the throttle plate isn't binding on some carbon when it gets hot.  It's at the smaller throttle openings that happens, since that is where the throttle lives 90% of the time in this country  :grin:


2007 ED30 | 2009 TDI 140

Offline Pudding

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Offline Clarkj93

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Re: P1545 and p1579 - engine cuts out and hunts for revs on idle
« Reply #3 on: June 20, 2022, 04:02:47 pm »
Yeah seems fine now, did a TB Alignment just in case anyway. Wiring looks okay undoing the clip and looking inside harness. Noticed a couple things:
1) unplugging the MAF has no difference on idle at all, thought it would drop and then sort itself out? But just continue at 800rpm as if nothing happens but eventually throws a code for it.
2) sounds a bit like hissing near the drive side of the engine, so slight it could be me going mad
3) seems to boost fine but on one occasion it did feel and sound like boost started to escape, couldn't get to do it again but I've had enough boost leak issues in the past to pick up on it straight away, again as it happened just once it made me doubt myself if it really happened or not!

Wouldn't have thought an air leak would cause TB codes though? Me going mad? Coinicendence? Or genuinely possibly linked?

Offline Pudding

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Re: P1545 and p1579 - engine cuts out and hunts for revs on idle
« Reply #4 on: June 21, 2022, 09:46:42 am »
The engine should definitely stumble if you yank the MAF when it's running.  If it doesn't, the ECU isn't using it to measure airflow and probably running a default strategy, which is likely if it was moaning about the throttle.  You could pull relay 100 (or disconnect the battery) which will reset the ECU.

Not sure about the rest.  The noises, leaks, misfires and inconsistency are all part and parcel of owing these bloody cars  :grin:


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Offline Clarkj93

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Re: P1545 and p1579 - engine cuts out and hunts for revs on idle
« Reply #5 on: Yesterday at 12:27:43 am »
Bought a throttle body from a TT with a BWA engine for 40 quid as well as a new gasket for 24 quid, it's the revision Q from Continental which I believe is the latest and greatest revision, mine was a J from VDO. Its had a decent amount of run time now and no issues so looks like we are all clear for now :happy2:

Offline Pudding

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Re: P1545 and p1579 - engine cuts out and hunts for revs on idle
« Reply #6 on: Yesterday at 08:39:44 am »
Blinkin eck, the gasket is expensive but good news mate  :happy2:

AG is the latest throttle body.  All TFSI/TSI use the same one, MK5 right up to MK7.5 R  :happy2:  I've got one from a 2019 R waiting to go on as part of my "Why is it so god dang slow off boost" investigation  :grin:


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Offline Clarkj93

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Re: P1545 and p1579 - engine cuts out and hunts for revs on idle
« Reply #7 on: Yesterday at 10:06:39 am »
Ah had no idea. Let me know if it's any improvement then!

Offline Pudding

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Re: P1545 and p1579 - engine cuts out and hunts for revs on idle
« Reply #8 on: Yesterday at 01:18:51 pm »
I only found that out myself when shopping for one  :grin:  I find ECS tuning's site is great for getting part numbers etc and they list all compatible vehicles so that you can search for , say a Skoda version, on ebay, which is usually way cheaper  :happy2:

Will do. I'm not expecting an improvement  :grin:  I think my actual issue is bad injectors but I'm working through the cheap/easy stuff first  :grin:


2007 ED30 | 2009 TDI 140